Process for dyeing leather.



UNITED STATES PATENT OFFICE.

PROCESS FOR DYEING LEATHER.

Specification of Letters Patent.

Patented Nov. 27, 1906.

Application filed January 21, 1905. Serial No. 242,068.

To all whom it may concern:

Be it known that I, FRANCIS J. OAKES, a citizen of the United States,and a resident of the borough of Manhattan, city, county, and State ofNew York, have invented a certain new and useful Process for DyeingLeather, of which the following is a specification.

The objects of my present invention are to produce a process which willobviate the injurious effects upon the leather incident to theapplication of the present processes for dyeing same and which result inimparting too much brittleness to the surface of the leather, removingundesirable portions of its tannin, and failing to impart a color ofsufificient permanence and intensity.

I attain the objects referred to by the hereinafter-described processes,in which I utilize the reactions realizable between the constituents ofan alkaline sulfid and compounds of a metal capable of combining in thepresence of resulting hydrogen sulfid to form an insoluble compound ofsaid metal as,for inst ance,a sulfid thereof or a hydroxid' after which,if desired, the leather may be still further treated by applying theretoa coloring-matter capable of forming a lake with the aforesaid resultingcompounds of said metal.

An example of my novel process and its method of application is asfollows: The leather after being stuffed or fat liquored is brushed overwith a dilute aqueous solution of a soluble alkaline sulfid-forinstance, a two-and-one-halfer-cent. solution of an ammonium sulfi (N H)Sx. It is then while still moist further treated by being brushed overwith a solution of a metallic compound or saltfor instance, an acetateof iron F62 OH3OOO 6 or Fe(CH COO) such a solution consisting of, say,one hundred arts of water containing ten parts of socalled black iron.After the treatment described the leather is allowed to dry, and after amoderate exposure to the atmosphere is ready for the usual finishingprocesses.

While the foregoing application of my process results in a dyesufficient for many purposes, it is often desirable for specificpurposes to impart to the leather a more intense or permanent color, inwhich case the leather while still moist and before the drying abovereferred to is additionally brushed over with an aqueous solution of anydesired dyestuffas, for instance, say, tenpercent.

nent.

solution of logwood extract-after which it is dried, as aforesaid, andis ready for the usual finishin processes.

It will be understood that the proportions and quantities of the agentsemployed may be varied according to requirement, as will be readilyascertained and appreciated by those skilled in the art.

It seems that the alkaline sulfid reacts with the fat liquors and greasein the leather to form alkaline salts, with a resulting liberation ofhydrogen sulfid, which is retained partly in consequence of the moistconditions. On the application of the solution containing the compoundof the metal there results in the presence of such hydrogen sulfid areaction resulting, among other things, in the formation of a sulfid ofsaid metal, or, should the latter be, for instance, chromium oraluminium, in the formation of a hydroxid thereof. These finallyresulting compounds of the metals introduced are of exceptionally softand plastic character and owing to this quality tend to fill up thepores of the leather and correspondingly improve its quality,diminishing brittleness, &c. In cases where additional coloring-matteror dyestuff is added by a third brushing over of the leather, asaforesaid, such coloring-matter or dyestuff should be of such characteras to be capable of forming a lake with the metallic compound formed, asaforesaid.

The color produced by my said process possesses the advantage of beingexceptionally resistant to the action of oxidizing and reducing agentsand correspondingly perma- Another noticeable advantage resulting frommy process is seen in the comparatively harmless action of the alkalinesulfid on the fiber of the leather, such sulfid acting merely as a mildalkali to cut the grease.

My process is applicable to all grades of leather and whether tanned bymeans of organic or mineral agents. It is advantageously applicablewithout the aforesaid final application of additional dyestuff toleathers prepared with tannic acids, in which case a very good black maybe secured, though there may occur in this case comparatively moreundesirable oxidation. As any coloring-matter complying with theaforesaid requirements may be employed in the final brushing, it will beappreciated that a large range of shades may be imparted.

Having thus described my process, what I claim as new, and desire tosecure by Letters Patent, is the following, viz:

1. The process of dyeing leather Which consists in a plying thereto,While moist, an alkaline suliid, and also a metal capable of combining,in the presence of hydrogen sulfid, to form an insoluble compound ofsaid metal, substantially as and for the purposes described.

2. The process of dyeing leather which consists in applying theretoWhile moist, an alkaline sulfid and also a metal capable of combining,in the presence of hydrogen sulfid, to form an insoluble sulfid of saidmetal.

3. The process of dyeing leather Which consists in applying thereto,While moist, a solution containing an alkaline sulfid, and also asolution containing a compound of a metal capable of combining, in thepresence of hydrogen sulfid, to form an insoluble compound of saidmetal.

4.. The process of dyeing leather which consists in applying thereto,while moist, a solution containing an alkaline sulfid and also asolution containing a compound of a metal capable of combining, in thepresence of hydrogen sulfid, to form an insoluble sulfid of said'metal;

5. The process of dyeing leather which consists in applying thereto,While moist, a

solution containing ammonium sulfid and also a solution containing asalt of iron.

6. The process of dyeing leather which consists in applying thereto,While moist, a solution containing ammonium sulfid and also a solutioncontaining acetate of iron.

7. The process of dyeing leather which consists in applying thereto,While moist, an alkaline sulfid, also a solution containing a compoundof a metal capable of combining, in the presence of hydrogen sulfid, toform an insoluble compound of said' metal, and also a coloring-mattercapable of forming a lake With the resulting compounds of said metal.

8. The process of dyeing leather which consists in applying thereto,While moist, an alkaline sulfid, a solution containing acetate of iron,and also a solution of logWood extract.

9. The process of dyeing leather which consists in applying thereto,While moist, an alkaline sulfid, and also a metal capable of combining,in the presence of hydrogen sulfid, .to form an insoluble compound ofsaid metal, substantially as and for the purposes described.

10. The process of dyeing leather which consists in applying thereto analkaline sulfid and also a metal capable of combining, in the presenceof hydrogen sulfid, to form an insoluble'sulfid of said metal.

11. The process of dyeing leather which consists in applying thereto,While moist, a solution containing ammonium sulfid and also a solutioncontaining a compound of a metal capable of combining in the presence ofhydrogen sulfid to form an insoluble sulfid of said metal.

12. The process of dyeing leather which consists in applying thereto,While moist, a solution containing ammonium sulfid, also a solutioncontaining a compound of a metal capable of combining, in the presenceofhydrogen sulfid, to form an insoluble sulfid of said metal, and also acoloring-matter capable of forming a lake with the resulting compound ofsaid metal.

FRANCIS J. OAKES.

Witnesses WALTER D. EDMONDS, ALLEN ROGERS.

